1. Field of the Invention
The present invention relates to a translation machine which enables to create a natural translated sentence, more particularly, the translation machine which is capable of analyzing a syntactic of a sentence whose words are modified in a complicated or ambiguous manner.
2. Description of the Related Art
The inventors of the present invention know a translation machine which is operated to enter a source language input from a keyboard into a translation module under the control of a main central processing unit (CPU). The translation module serves to translate the source language into a target language through the use of dictionaries and rules such as grammatical rules and tree-structure transforming rules stored in a memory.
In translation, the syntactic of the source language is analyzed in the translation module as follows. Words composing one sentence contained in the read source language are stored in a buffer. Using the dictionary stored in the memory, the translation module serves to derive the part of speech of each word stored in the buffer. Then, the proper grammatical rules are picked out of the memory for setting up the modifying relation among the parts of speech of the words. Based on the picked grammar rules, a parse tree is created indicating how the words composing the sentence are modified. The syntactic analysis process for the source language done in the known translation machine is the bottom-up analysis of a syntactic based on the local information, that is, the grammar rules about the parts of speech and the phrases of the words.
The bottom-up analysis of a syntactic based on the local information implemented in the known translation machine has the following shortcomings.
To analyze a sentence having a complicated or ambiguous modifying structure of words composing the sentence, the modifying relation is often erroneously recognized. In a case that one phrase of the sentence is erroneously recognized, the syntactic analysis is carried out on the basis of the erroneously-recognized modifying relation of one phrase, resulting in creating the erroneous syntactic analysis.
Alternatively, in a case that the erroneously-recognized modifying relation of one phrase results in bringing about failure of the syntactic analysis, thereby failing in creation of a parse tree, and the translation is carried out for each phrase. Hence, the resulting translated sentence does not have the proper structure in the target language.
For example, consider the sentence of the source language "After independence from the U.K. in 1962, the country started election." This sentence consists of a prepositional phrase, a comma, and a declarative sentence.
The foregoing known translation machine may fail in analyzing a syntactic, because the translation machine does not store in the memory the grammatical rules appropriate to form one parse tree about the example sentence. As such, the known translation machine operates to divide the example sentence into:
______________________________________ Three prepositional phrases "After independence" "from the U.K." "in 1962" Comma "," Declarative sentence "the country started election." ______________________________________
Then, the syntactic analysis is carried out for each phrase and the declarative sentence. As a result, the known translation machine offers the translated sentence of: EQU 1962
which does not have a natural Japanese syntactic as a target language.